It is desirable, especially in the case of patients connected to anesthesia apparatuses or respirators, to measure the concentration of individual gases or of a plurality of gases in the breathing gas flow by means of suitable gas analyzers. It has been known that condensed water from breathing gas drawn off by means of vacuum is collected in water traps to protect such gas analyzers and also to prevent possible errors in measurement.
To recognize and guarantee the ability of such water traps to function, it would be advantageous if the operating state and the degree of filling of the tank receiving the separated water were displayed.
The prior-art water traps do not meet either the desired requirements in terms of accuracy and they do not permit more than two different operating states to be recognized, and they generate false alarms because of the principle of display used and/or are impractical in handling.
A prior-art water trap is described in U.S. Pat. No. 4,886,528, in which no specific filling level recognition is provided. With the tank filled, the gas flow resistance increases greatly, so that no more gas can pass through the water trap, i.e., only two operating states, namely, able to function and unable to function, can be recognized.